8.5 fl oz sugar syrup (dissolve 1 cup of sugar in 8.5 fl oz boiling water and let it cool)
And this is how it’s done:
Let the coffee steep in the vodka for 6 hours. Then, slowly filter out the coffee and mix vodka with sugar syrup. You can warm the mixture up (carefully) to ensure that it blends properly. Pour into a nice bottle. Done. In case you find the liqueur too strong, you can reduce the steep time.